Obesity has been assumed epidemic proportions. The National Health and Nutrition Examination Survey (NHANES 1999-2000) showed that 31% of American adults were obese, defined by a body mass index (BMI)> 30 kg/m2, and 34%, overweight (BMI 25 -29.9 kg/m2). This means that 65% of adults had excess weight, 20% more than 20 years ago. Obesity can produce about 300 000 deaths annually and has implications in several diseases such as hypertension, coronary artery disease (CAD), hyperlipidemia, diabetes mellitus (DM), depression, breast, colon, prostate, endometrium and gallbladder apnea sleep, chronic back pain and osteoarthritis.
In 1998 the American Heart Association has classified obesity as a major modifiable risk factor of CHD. Therefore, several investigations have been conducted to evaluate the role of diet and exercise in the treatment of obesity.
There are numerous observational data support the relationship between physical inactivity and obesity. A review of 8 prospective studies of the American College of Sports Medicine (ACSM) showed an association between low physical activity and risk of obesity.
In a clinic in Dallas analyzed data from more than 5 300 people of both sexes between 1970 and 1994 and found that, for every increase of one minute in exercise time between the first and second assessment was reduced by 21% increase the probability of 10 kg during a study period of 7.6 years on average.
A randomized controlled trial conducted at Duke University showed a dose-response relationship between weekly volume of exercise and weight change in overweight subjects who did not diet. To avoid gaining 2.5 lb (weight gained by subjects who had not been exercised for 6 months) was necessary to walk or jog 6 to 7 miles per week.
A sedentary lifestyle is also at epidemic levels, with prevalence rates parallel those of obesity. Over 60% of American adults reported physical activity on an infrequent basis and 25% are completely sedentary. These figures represent participation in sports, fitness and recreational activities but do not quantify the energy expended in activities of daily living. Haskell estimated that replacing 2 minutes per hour of employees sending emails for a walk to the office of the co-worker could determine a difference of 5 kg of weight in a decade.
physical activities in the treatment of obesity
Weight loss
Several studies suggest that exercise alone is a rather inefficient method for losing weight. To burn 1 pound of fat should be approximately 35 miles of jogging or walking.
A panel of experts examined 12 randomized controlled studies on the effects of aerobic exercise not accompanied by diet on weight loss. As a result, found that people who exercised lost an average of 5 pounds more in 9 months than those who did not. Similar results were obtained in 2 meta-analyzes.
In a recent randomized controlled trial in 52 obese men, 14 patients assigned to exercise to burn 2 940 kcal / day lost an average of 16 lb for 12 weeks.
Bouchar and colleagues conducted a study in which 5 men were sent to a residential complex where they had to make 2 workouts of 53 minutes, 6 times a week for 100 days. Dietary intake was monitored strictly and should remain constant. After 3 months, participants had lost an average of 8 kg. The significant weight loss in this controlled study may be partially explained by the increased amount of exercise over other tests.
In addition, lends credence to the belief that increased physical activity is often accompanied by a concomitant increase in food intake. Obese subjects commonly report a lower caloric intake than real.
Although the exercise seems to play a modest role in weight loss could have a crucial role in maintaining the loss.
A recent meta-analysis of 6 randomized controlled trials, comparing the effects of diet compared to the latter more exercise to maintain weight loss for over a year, showed that diet plus exercise group achieved better results in maintaining weight loss during follow-up of at least one year than those who only made diet. However, the differences were significant in only 2 of the 6 studies.
A review of 46 observational studies and randomized trials showed a trend toward better maintenance of weight in the groups who performed physical activity compared with controls, the activity level proportional to the amount of weight lost.
Most of the data supporting the role of exercise in maintaining weight loss comes from observational studies and post hoc analysis of trials of weight loss.
The National Weight Control Registry contains information on more than 3 000 people who maintained a weight loss> 30 lb for> 1 year. Individuals who maintain weight loss behavior strategies employing 3. First, eat a diet low in fat and high in carbohydrates. Second, perform frequent self-assessment of body weight and food intake. Finally, reach high levels of regular physical activity. 91% of participants reported exercising regularly, for example, an hour of brisk walking-like weapon key to maintaining weight loss.
Exercise stimulates fat loss and increase lean muscle mass, which may affect the absolute amount of weight lost. In contrast, when you lose weight by diet only, up to 30% of the loss can be due only to loss of muscle mass.
The results of observational studies in thousands of people showed beneficial effects of physical activity on body fat distribution determined by waist circumference (WC), waist / hip ratio (WHR) and waist / thigh. However, the results of controlled studies were ambiguous.
A controlled trial in 131 obese men randomized to diet alone, exercise alone or a sedentary control group after one year showed a greater average weight loss in the diet group (7.2 kg) compared to the exercise group (4 kg). However, the men of the first group lost 1.3 kg of muscle mass and those who exercised gained 0.1 kg of muscle. Therefore, the actual difference between the weight loss became less (5.9 kg vs. 4.1 kg).
A study on the effect of resistance exercise on body composition in 28 young men and older showed that although there were only small changes in weight, WC and WHR, both groups showed a 20% reduction in abdominal fat deposits measured by computed tomography. This was confirmed in a study in 173 obese postmenopausal women.
There are numerous observational evidence supporting the fact that regular physical activity can reduce mortality from all causes and in particular, cardiovascular mortality (CV) of 20% to 30%.
For example, the Aerobics Center Longitudinal Study of 24 years duration involving 26 000 obese men with good CV (demonstrated by treadmill test) showed overall mortality and CV of about 50% of those submitted by men untrained normal weight. Other studies have suggested that physical activity, independently of its action on weight, has favorable effects on blood pressure, insulin resistance, lipid profile, the severity of sleep apnea and the incidence of colon cancer, breast cancer, osteoarthritis and osteoporosis.
The loss of 5% or 10% of initial weight can produce substantial improvements in risk factors for cardiovascular disease and DBT and lead to a reduction or discontinuation of medication.
The Diabetes Prevention Program Trial included 3234 non diabetic subjects and BMI of 34 kg/m2 average elevation of fasting plasma glucose test or glucose tolerance. The group assigned to changes in lifestyle (low-fat diet + regular exercise of at least 150 min / week) had a 58% reduction in the risk of DBT compared to placebo and the group with metformin reduced the incidence of DBT 31%.
Most studies of exercise for the management of obesity have focused on aerobic exercise.
In weight training program combined with diet restriction does not change the absolute loss of weight compared with diet alone or diet plus aerobic exercise. However, resistance training has a favorable effect on body composition in obese subjects who lose weight by food restriction. It was shown that for every 10 kg lost with diet alone, 25% is lean body mass. Another study showed that this loss of lean mass could be avoided with the addition of a combined program of aerobic exercise and strength training.
The researchers observed a mass loss of 69% fat diet, 78% with diet and aerobic exercise, and 97% with diet, aerobic exercise and weights. Studies have not shown that increasing the percentage of lean mass prevents the decrease in basal metabolic rate associated with weight loss.
Initial results of studies on resistance training and CV risk markers suggest that the improvement of blood glucose and markers of inflammation depends more weight loss than the exercise itself.
Data on physical activity and mortality in obese individuals suggest that a relationship exists between exercise volume and mortality and requires a weekly energy expenditure of at least 4 200 kcal (30 minutes or 2 miles of brisk walking 5 times a week ) to produce a significant reduction in mortality. There is a similar relationship between volume of exercise and modification of cardiovascular risk factors. However, it seems require more exercise to lose weight and keep it off. In the National Weight Control Registry, 52% of those who manage to keep the weight spent 10 500 kcal / week for women and 13 860 kcal / week men, equivalent to 60 to 80 minutes of moderate activity (brisk walk).
In conclusion, regular exercise appears to be critical for preventing weight gain and to maintain weight loss and to promote CV health.
In 1998 the American Heart Association has classified obesity as a major modifiable risk factor of CHD. Therefore, several investigations have been conducted to evaluate the role of diet and exercise in the treatment of obesity.
There are numerous observational data support the relationship between physical inactivity and obesity. A review of 8 prospective studies of the American College of Sports Medicine (ACSM) showed an association between low physical activity and risk of obesity.
In a clinic in Dallas analyzed data from more than 5 300 people of both sexes between 1970 and 1994 and found that, for every increase of one minute in exercise time between the first and second assessment was reduced by 21% increase the probability of 10 kg during a study period of 7.6 years on average.
A randomized controlled trial conducted at Duke University showed a dose-response relationship between weekly volume of exercise and weight change in overweight subjects who did not diet. To avoid gaining 2.5 lb (weight gained by subjects who had not been exercised for 6 months) was necessary to walk or jog 6 to 7 miles per week.
A sedentary lifestyle is also at epidemic levels, with prevalence rates parallel those of obesity. Over 60% of American adults reported physical activity on an infrequent basis and 25% are completely sedentary. These figures represent participation in sports, fitness and recreational activities but do not quantify the energy expended in activities of daily living. Haskell estimated that replacing 2 minutes per hour of employees sending emails for a walk to the office of the co-worker could determine a difference of 5 kg of weight in a decade.
physical activities in the treatment of obesity
Weight loss
Several studies suggest that exercise alone is a rather inefficient method for losing weight. To burn 1 pound of fat should be approximately 35 miles of jogging or walking.
A panel of experts examined 12 randomized controlled studies on the effects of aerobic exercise not accompanied by diet on weight loss. As a result, found that people who exercised lost an average of 5 pounds more in 9 months than those who did not. Similar results were obtained in 2 meta-analyzes.
In a recent randomized controlled trial in 52 obese men, 14 patients assigned to exercise to burn 2 940 kcal / day lost an average of 16 lb for 12 weeks.
Bouchar and colleagues conducted a study in which 5 men were sent to a residential complex where they had to make 2 workouts of 53 minutes, 6 times a week for 100 days. Dietary intake was monitored strictly and should remain constant. After 3 months, participants had lost an average of 8 kg. The significant weight loss in this controlled study may be partially explained by the increased amount of exercise over other tests.
In addition, lends credence to the belief that increased physical activity is often accompanied by a concomitant increase in food intake. Obese subjects commonly report a lower caloric intake than real.
Although the exercise seems to play a modest role in weight loss could have a crucial role in maintaining the loss.
A recent meta-analysis of 6 randomized controlled trials, comparing the effects of diet compared to the latter more exercise to maintain weight loss for over a year, showed that diet plus exercise group achieved better results in maintaining weight loss during follow-up of at least one year than those who only made diet. However, the differences were significant in only 2 of the 6 studies.
A review of 46 observational studies and randomized trials showed a trend toward better maintenance of weight in the groups who performed physical activity compared with controls, the activity level proportional to the amount of weight lost.
Most of the data supporting the role of exercise in maintaining weight loss comes from observational studies and post hoc analysis of trials of weight loss.
The National Weight Control Registry contains information on more than 3 000 people who maintained a weight loss> 30 lb for> 1 year. Individuals who maintain weight loss behavior strategies employing 3. First, eat a diet low in fat and high in carbohydrates. Second, perform frequent self-assessment of body weight and food intake. Finally, reach high levels of regular physical activity. 91% of participants reported exercising regularly, for example, an hour of brisk walking-like weapon key to maintaining weight loss.
Exercise stimulates fat loss and increase lean muscle mass, which may affect the absolute amount of weight lost. In contrast, when you lose weight by diet only, up to 30% of the loss can be due only to loss of muscle mass.
The results of observational studies in thousands of people showed beneficial effects of physical activity on body fat distribution determined by waist circumference (WC), waist / hip ratio (WHR) and waist / thigh. However, the results of controlled studies were ambiguous.
A controlled trial in 131 obese men randomized to diet alone, exercise alone or a sedentary control group after one year showed a greater average weight loss in the diet group (7.2 kg) compared to the exercise group (4 kg). However, the men of the first group lost 1.3 kg of muscle mass and those who exercised gained 0.1 kg of muscle. Therefore, the actual difference between the weight loss became less (5.9 kg vs. 4.1 kg).
A study on the effect of resistance exercise on body composition in 28 young men and older showed that although there were only small changes in weight, WC and WHR, both groups showed a 20% reduction in abdominal fat deposits measured by computed tomography. This was confirmed in a study in 173 obese postmenopausal women.
There are numerous observational evidence supporting the fact that regular physical activity can reduce mortality from all causes and in particular, cardiovascular mortality (CV) of 20% to 30%.
For example, the Aerobics Center Longitudinal Study of 24 years duration involving 26 000 obese men with good CV (demonstrated by treadmill test) showed overall mortality and CV of about 50% of those submitted by men untrained normal weight. Other studies have suggested that physical activity, independently of its action on weight, has favorable effects on blood pressure, insulin resistance, lipid profile, the severity of sleep apnea and the incidence of colon cancer, breast cancer, osteoarthritis and osteoporosis.
The loss of 5% or 10% of initial weight can produce substantial improvements in risk factors for cardiovascular disease and DBT and lead to a reduction or discontinuation of medication.
The Diabetes Prevention Program Trial included 3234 non diabetic subjects and BMI of 34 kg/m2 average elevation of fasting plasma glucose test or glucose tolerance. The group assigned to changes in lifestyle (low-fat diet + regular exercise of at least 150 min / week) had a 58% reduction in the risk of DBT compared to placebo and the group with metformin reduced the incidence of DBT 31%.
Most studies of exercise for the management of obesity have focused on aerobic exercise.
In weight training program combined with diet restriction does not change the absolute loss of weight compared with diet alone or diet plus aerobic exercise. However, resistance training has a favorable effect on body composition in obese subjects who lose weight by food restriction. It was shown that for every 10 kg lost with diet alone, 25% is lean body mass. Another study showed that this loss of lean mass could be avoided with the addition of a combined program of aerobic exercise and strength training.
The researchers observed a mass loss of 69% fat diet, 78% with diet and aerobic exercise, and 97% with diet, aerobic exercise and weights. Studies have not shown that increasing the percentage of lean mass prevents the decrease in basal metabolic rate associated with weight loss.
Initial results of studies on resistance training and CV risk markers suggest that the improvement of blood glucose and markers of inflammation depends more weight loss than the exercise itself.
Data on physical activity and mortality in obese individuals suggest that a relationship exists between exercise volume and mortality and requires a weekly energy expenditure of at least 4 200 kcal (30 minutes or 2 miles of brisk walking 5 times a week ) to produce a significant reduction in mortality. There is a similar relationship between volume of exercise and modification of cardiovascular risk factors. However, it seems require more exercise to lose weight and keep it off. In the National Weight Control Registry, 52% of those who manage to keep the weight spent 10 500 kcal / week for women and 13 860 kcal / week men, equivalent to 60 to 80 minutes of moderate activity (brisk walk).
In conclusion, regular exercise appears to be critical for preventing weight gain and to maintain weight loss and to promote CV health.
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